Columnar Flip-Chip Electrodes With Sintered Bonding Against Electromigration
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Solution Overview
Problem
Conventional semiconductor devices using solder for flip-chip bonding are prone to electromigration due to the low melting point of solder, leading to reduced bonding strength and increased parasitic resistance as semiconductor elements shrink and circuit integration increases.
Innovation Solution
A semiconductor device with a sintered metal powder bonding layer, where electrodes have a columnar portion and a recessed portion to increase contact area and anchoring effect, reducing current density and electromigration, and using materials like silver or copper for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solder is used for the bonding layer, then the bonding process is simple and cost-effective, but electromigration occurs due to the low melting point of solder
Solution Approach 1:
The patent changes the material parameter of the bonding layer from solder (low melting point) to sintered metal powder (high melting point). This parameter change eliminates electromigration while maintaining bonding functionality, directly resolving the contradiction between manufacturing simplicity and electromigration resistance.
Solution Approach 2:
The patent uses composite structure where the bonding layer is formed by sintered metal powder particles. This composite material approach provides both the mechanical bonding strength and the electrical conductivity needed, while avoiding the electromigration issues of traditional solder materials.
2Productivity
If semiconductor element size is reduced and circuit integration is increased, then device functionality is enhanced, but current density increases and electromigration becomes more likely
Solution Approach 1:
The patent changes the bonding layer material parameters (melting point, electrical conductivity) to withstand higher current densities. The sintered metal powder bonding layer has superior electrical and thermal properties compared to solder, enabling it to handle the increased current density from miniaturized, high-integration devices without electromigration.
3Ease of manufacture
If the bonding layer uses traditional solder, then the melting point is low and bonding is easy, but bonding strength decreases over time due to electromigration
Solution Approach 1:
The patent changes the bonding layer from solder to sintered metal powder, fundamentally altering the material parameters. The sintered metal powder provides superior long-term bonding strength while maintaining manufacturability through sintering processes, directly addressing the strength degradation issue caused by electromigration in traditional solder bonds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses electromigration and improves bonding strength, reducing parasitic resistance and noise in the semiconductor device.
Implementation Method 1
Electromigration is a phenomenon in which loss such as a void is generated in a conductor due to ions gradually moving since momentum is exchanged between the electrons moving in the conductor and the metal atoms
Implementation Method 2
The bonding layer is a sintered body of a metal powder
Data Source
AI summary
A semiconductor device includes an electric conductor, a semiconductor element, and a bonding layer. The electric conductor has a main surface and a rear surface opposite to the main surface in a thickness direction. The semiconductor element includes a main body and electrodes. The main body has a side facing the main surface of the conductor, and the electrodes each protrude toward the main surface from the side of the main body to be electrically connected to the main surface. The bonding layer is held in contact with the main surface and the electrodes. Each electrode includes a base portion in contact with the main body, and a columnar portion protruding toward the main surface from the base portion to be held in contact with the bonding layer, which is a sintered body of a metal powder.